Method of printing pharmaceutical forms



United States Patent 3,17 3,839 METHOD OF PRlNTlNG PHARMACEUTICAL FORMSArnold E. Nicholson, Philadelphia, Pa., assignor to Smith Kline 81French Laboratories, Philadelphia, Pin, a corporation of Pennsylvania NoDrawing. Filed Jan. 9, 1962, Ser. No. 165,226 3 Claims. (Cl. 167-82)This invention relates to a novel method of printing pharmaceuticalforms such as tablets, pills and the like and to the product of thismethod. More particularly, this invention provides a versatile,simplified method of printing pharmaceutical forms which greatly reducesthe time previously required.

The technique of the prior art involved in the ink monogramming oftablets has been to apply a coat of ink receptive material, preferablyshellac, over the coated tablets and printing the desired ink indiciathreon. Shellac is used not only because of its ink receptive propertiesbut also because it prevents chipping, smearing and dusting of thetablets during the printing operation.

The present method of applying the shellac to the pharmaceutical formsis very time consuming. The coated tablets, in particular sugar coatedtablets, must be thoroughly dried before the application of the shellaccoat in order to prevent frosting of the shellac by the presence ofmoisture. The present method consists of applying the desired tabletcoating, removing the tablets from the coating pan after the final colorcoats have been applied and then drying the tablets overnight. Thetablets after being completely dried are then placed in a specialshellacking pan and one or more coats of wax free shellac are appliedout of a suitable organic solvent, usually isopropyl alcohol. Since thisshellac is incompatible with water it is absolutely necessary that thetablets have been thoroughly dried before the application of theshellac. The time required to assure complete drying is approximately 24hours. The shellac coated tablets are then removed from the coat ingpan, monogrammed and polished.

The novel method of printing tablets and the tablet in accordance withthis invention eliminates the above time consuming procedure and makesit possible to print tablets rapidly and inexpensively. The timerequired to print the tablets has been reduced from days to a matter ofhours. The novel process of printing tablets as disclosed by theapplicant eliminates the necessity of tablets being dried overnightbefore the application of the shellac. Another advantage of this novelinvention is that less handling of the tablets is required since they donot have to be racked and repanned a second time. A further advantage ofthis invention is that it permits the shellac coating of thepharmaceutical forms in the same pan in which they are sugar coatedfollowing the normal pan drying cycle thus eliminating the necessity ofspecial shellacking pans. The method and tablet of this invention is,therefore, markedly less expensive than those disclosed in the prior artbecause of the great reduction in operating time and the elimination ofspecial shellac coaing pans discussed above.

The method of printing the solid pharmaceutical forms such as compressedtablets, pills, troches and the like in accordance with this inventioncomprises preparing a water soluble form of shellac and applying theshellac directly to the tablets immediately after they have been coatedand given the usual pan drying period. It is a con- 'ice tinuousoperation starting with the coating of the medicinal core to the finalshellac coating before the tablets are removed from the pan. Since theshellac is water soluble it does not cause frosting of the coatedtablets if they are not thoroughly dried, in fact, it prevents thetablets from frosting. The shellac coated tablets are then removed fromthe coating pans, printed and polished.

The water soluble shellac is prepared by dissolving wax free shellac inwater and ammonia until a solution results. The ratio of water andammonia to the wax free shellac would be evident to one skilled in theart using just enough necessary to dissolve the shellac. Preferablytwice as much water and 28% ammonia solution (U.S.P.) used in a ratio ofabout 10:1 to about 30:1 is used to dissolve the shellac. If desired,alcohol may be added to hasten the evaporation of the water solubleshellac coating on the tablets.

The printing and polishing of tablets referred to above are very wellknown conventional steps in the tableting art. For example, the printingcan be accomplished simply by biasing the tablets against a printingmechanism such as a stamp or roller having the desired monogram andsaturated with any of the well known edible inks. Tablet printingmachines are available to perform a continuous operation of printing andconveying the tablets, i.e., mass production.

The polishing operation is well known to the art and the materials usedmay be, for example, beeswax, carnauba wax, ozokerite or ceresin.Preferably a combination of beeswax and carnauba wax in variousproportions is used.

The coated tablets referred to in this invention can have any coatingwell known to the art, such as for example, sugar coating, entericcoating, film coating or the many difierent forms of sustained releasecoatings.

The solid pharmaceutical forms which are printed using this novelprocedure comprises coated tablets, pills, troches and the likesubstantially and completely coated with water soluble shellac andhaving an ink identifying monogram marked upon a portion of the shellaccoating. If desired, the tablet can be finished with a polishing coat ofwax.

While this invention applies mainly to the phamaceutical industry it isto be understood that this method of printing can be applied to anyindustry which desires to ink monogram their edible products.

The following is an example which is not limiting but is usedspecifically to illustrate the water soluble shellac coating compositionand method of application. It will make it obvious to one skilled in theart the full practice of the method of this invention.

Example Ingredients: Amounts, gm. Shellac, dry, white, wax free 500Water, purified 950 Ammonia solution, 28% 50 The shellac, Water andammonia solution are heated on a steam bath until a thick molasses-likesolution results. The solution is then filtered and the final solutionis approximately shellac. To 15 grams of this water soluble shellac isadded 10 grams of purified water and this solution is then diluted withenough isopropyl alcohol to make 500 ml.

Tablet cores containing chlorpromazine and filler are placed in arotating 12 inch coating pan and are sugar coated and dried. Whilecontinuing to rotate the coating pantthetwater soluble shellac solutionis thenaddeddirectly to the coated cores in the rotating pan and allowedto dry while rotating in the pan. The tablets are then removed from thecoating pan and ink monogrammed. A polish coating of beeswax is thenapplied to the printed tablets.

What is claimed is:

1. In a method of preparing printed pharmaceutical forms comprisingcoating pharmaceutical forms rotating in a coating pan to give coatedforms, drying said coated forms and ink printing said coated forms, thenovel'step of covering said coated forms with a Water soluble shellacsolution prior to said ink printing.

2; The method of claim 1 characterized in that all coating operationsincluding the application ofthe water soluble shellac are continuous.

3. The method of claim 1 further characterized in tha the pharmaceuticalforms are coated with a sugar coating.

References Cited in the file of this patent UNITED STATES PATENTS3,015,609 Sanders l Jan. 2, 1962

1. IN A METHOD OF PREPARING PRINTGED PHARMACEUTICAL FORMS COMPRISINGCOATING PHARMACEUTICAL FORMS ROTATING IN A COATING PAN TO GIVE COATEDFORMS, DRYING SAID COATED FORMS AND INK PRINTING SAID COATED FORMS, THENOVEL STEP OF COVERING SAID COATED FORMS WITH A WATER SOLUBLE SHELLACSOLUTION PRIOR TO SAID INK PRINTING.